Sheep's Foot Ascidian

Polycarpa mytiligera, commonly known as the "Sheep's foot ascidian" or "Mytilid ascidian," is a species of sea squirt (a tunicate belonging to the subphylum Tunicata) that is found in various marine environments, including the waters of the 🌊 Red Sea. Tunicates are known for their distinctive sac-like structures and are filter feeders, playing an important role in marine ecosystems.

Appearance: Polycarpa mytiligera has a unique appearance that resembles the foot of a sheep, which is where the common name is derived from. It typically exhibits a leathery, elongated body ranging from a few centimeters up to 10 centimeters in size. The body is often a creamy white or yellowish color, with a tough outer tunic that can have embedded sand grains or other small particles providing a form of camouflage with the surrounding environment.

The species has two siphons, an incurrent and an excurrent, that are used for the intake of water and expulsion of filtered water, respectively. These siphons are often edged with orange, brown, or purple, adding a touch of color to its otherwise muted appearance. Its body texture can range from smooth to slightly wrinkled.

Habitat: In the 🌊 Red Sea, Polycarpa mytiligera is typically found attached to hard substrates, such as coral reefs, rock surfaces, or under overhangs. It favors shallow to moderate depths but can also be found at greater depths, providing the conditions are suitable. The presence of P. mytiligera is an indication of a healthy reef ecosystem, as tunicates are sensitive to environmental changes and pollution.

Diet and Ecology: As a filter feeder, P. mytiligera feeds on plankton and organic particles suspended in the water. It pumps water through its incurrent siphon, filters out food particles using a mucous net produced by the endostyle, and then expels the filtered water through the excurrent siphon. Its feeding contributes to the control of phytoplankton populations and thus plays a part in maintaining water clarity and quality.

Reproduction: Like other tunicates, Polycarpa mytiligera is a hermaphrodite that can produce both sperm and eggs. The species reproduces through a process of broadcast spawning, where eggs and sperm are released into the water column, allowing fertilization to occur externally. The resulting larvae are free-swimming and, after a brief planktonic stage, will settle onto a suitable substrate and metamorphose into the adult form.

Conservation: While not a primary target for human exploitation, Polycarpa mytiligera, like all marine organisms in the 🌊 Red Sea, can be sensitive to changes in environmental conditions such as temperature, salinity, and water quality. Efforts to monitor and protect reef habitats in the 🌊 Red Sea help to ensure the persistence of species like P. mytiligera within this dynamic ecosystem.